Baseball Gauge Wins Above Replacement (gWAR)

Replacement Level

Replacement level is set at a .294 winning percentage in order to maintain continuity with Baseball-Reference's version of WAR (bWAR). Also, Baseball-Reference's year and league "level of competition" adjustments are also included.

Pythagorean Winning Percentage

The PythagenPat method is used when converting runs to wins and also uses .285 as the exponent in the formula.

WAG (Wins Above Greatness) Formula

Fielding

The Fielding component uses a multi-year average of Defensive Regression Analysis (DRA) to estimate a player's value (in runs saved) above/below average. DRA was created by Michael Humphreys and its method is described in the book Wizardry.

Positional Adjustment

In order ot maintain continuity, Baseball-Reference's positional adjustments are used. By default, positional adjustments are NOT INCLUDED in offensive and fielding WAR. This can be changed by using the customized metric option.

Pitching

There are 2 versions of Pitching WAR. The first is based on runs allowed à la Baseball-Reference. The second is based on FIP (Fielding Independent Pitching), à la FanGraphs. By default, the runs allowed version is included in gWAR, but this can be changed when using the customized metric option.

Both versions are calculated using the same formula. The only difference is the runs allowed above average (RAA) variable.

WAG (Wins Above Greatness) Formula

Per 162 Games

The rate of a statistic over the course of 162 games. This is based on the player's entire career. Position players and pitchers games played are treated differently.

Batting Seasons = Games appeared as a position player divided by 162. (G / 162)
Pitching Seasons = Games appeared as a pitcher plus Games Started, divided by 68. ((G + GS) / 68)
Seasons = Batting Seasons + Pitching Seasons
Total = Career Total in that statistic

per 162 = Total / Seasons

JAWS

Developed by Jay Jaffe in 2004 at Baseball Prospectus. It is meant to gauge a player's Hall of Fame credentials by comparing them to Hall of Famers at the same position. JAWS is the average of a player's career total Wins Above Replacement and the total of their seven best seasons (peak).

Since not all positions are represented equally in the Hall of Fame, JAWS requires a minimum # of players at each position. Currently, the position with the most players in the Hall of Fame is RF, with 25. To meet the required minimum, the calculation includes the average position player's JAWS score for each player that it is short of the minimum (Starting and Relief Pitchers are not subject to this minimum requirement).

For example, there are currently 15 catchers in the Hall of Fame, which is 10 players short of the minimum. The JAWS calculation will find the average of the 15 catchers AND 10 average Hall of Fame position players to determine the average Hall of Fame catcher's JAWS score.